From French-speaking Dragon City FB group. Not sure how accurate this is, but:
The following dragons will be available on the Oni island:
- Poo Dragon (R, #95)
- Night Dragon (VR, #589)
- Kyuubi Dragon (new, E, #724)
- Penumbra Dragon (L, #613)
There will be 5500 coins for collection (9x600 + 150 for tutorial) and the following picture shows the cheapest path. The blue part is what's achievable for free; the red requires spending real money.
The cinema on the Freebies island will give out the Recycle Dragon (there they mention "Recyclable", but I think they meant "Recycle" - I don't know if any of the dragons are actually recyclable :).
Finally, a breeding event will be Recycle+Kyuubi=Jumping Dragon.
Get ready :)